Off-Balance Sheet Arrangements Commitments Guarantees and Contingencies (Narrative) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Commitments And Guarantees [Line Items]
Credit card guarantees	$ 9.1	$ 8.5
Fully collateralized credit card guarantees	$ 8.2	$ 1.3